Also I would give the advantage to USB only because if you plan on using it with other computers that either don't have a free PS2 port OR don't have PS2 ports period as with some Macs you will be able to use it. Otherwise I don't think input transmission speed is a factor but I could be wrong...I'm sure the difference is so small that you don't have to worry about it. As far as drivers, this should work with just about any computer via generic keyboard drivers included in every operating system. If you find one that doesn't work let us know.

I had viewed the sticky, but I found it not clear about Legends (it seemed it applied to Decks).

Will the USB keyboard slow down other USB devices in the chain (or the device attached to the same controller, AFAIK on my PC there are 4 main USB controllers [I may have the terminology wrong here] and 8 USB sockets, where each 2 share a controller), is one of my worries. And I have an empty PS2 port now.

In the end, I think USB is more future proof. I plan to use my Deck Keyboards for a really long time...